Preheat the oven to 350ºF (180ºC). Prepare a 9×13 inch pan with non-stick cooking spray or parchment paper. Set aside.

Place the oreos in a ziploc bag and crush using a rolling pin, meat tenderizer or the bottom of a cup.

In a small mixing bowl combine the flour, baking powder, baking soda, and salt.

In a large mixing bowl combine the butter, sugar, and vegetable oil, beat using an electric mixer, 1-2 minutes until fluffy.

Add in the egg whites, sour cream, milk, and vanilla extract. Beat with the electric mixer.

Gradually add the flour mixture and the crushed oreos to the wet ingredients, mixing just until the flour is incorporated.

Pour the batter into the prepared pan and spread evenly with a spatula.

Bake for 32-39 minutes or until a toothpick inserted into the center comes out clean. Light pans take longer to bake than dark pans.

Allow the cake to cool completely before frosting.

Place the oreos in a ziploc bag and crush using a rolling pin, meat tenderizer or the bottom of a cup. Alternatively, place the oreos in a food processor or blender, pulse into crumbs. The oreos that go into the frosting should be finer than the oreos in the cake, but small pieces are okay!

In a mixing bowl, combine the butter, vanilla extract and salt, beat using an electric mixer until fluffy, 1-2 minutes.

Gradually add 4 cups of powdered sugar mixing on low until combined.

Add in ¼ cup of heavy cream, beating on high until the frosting is whipped and fluffy.

Reserve ¾ cup of frosting for decorating and spread the rest of the frosting over the cake.

For an extra fancy presentation, after I evenly spread the oreo frosting over the cake, I lightly sprinkled oreo crumbs on the top. Then I cut the cake into squares and in the center of each piece I added a frosting swirl and a mini oreo.